The developmental histories of enzyme activities of murine odontogenic and paradental tissues will be investigated at the optical and ultrastructural levels. We will utilize the Swiss albino (a wild type mouse) and a mutant, the "hairless" strain which has been demonstrated to possess developmental defects involving bone and dental tissues. The enzymes studied will be phosphatases (adenosine triphosphatase, acid phosphatase, alkaline phosphatase, thiamine pyrophosphatase and 5'-nucleotidase), a sulfatase (aryl sulfatase), and amylolytic enzyme (N-acetyl-B-glucosaminidase) and an oxidative enzyme (succinic dehydrogenase). The comparison of the developmental histories of enzyme activities of the two strains studied should provide a raison d'etre for the ensuing morphological defects and thus aid in the elucidation of the mechanisms of developmental anomalies. BIBLIOGRAPHIC REFERENCES: Provenza, D. V., Gartner, L. P., Hiatt, J. L. and Seibel, W. 1976. Adenosine triphosphatase activity in mouse molar development. J. Dent. Res. 55: 154. Payne, T. M., Gartner, L. P., Hiatt, J. L., Seibel, W. and Provenza, D. V. 1976. Succinic dehydrogenase activity in odontogenic tissues of the hairless mouse. J. Dent. Res. 55: 154.